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	 list	p=16f84a
	 #include		<p16f84a.inc>              
	 __CONFIG			_CP_OFF & _WDT_OFF
w		equ	0
f		equ	1
Speed_value	equ	d'5'
Counter		equ	h'0c'
Shift_cunter	equ	h'0d'
W_temp		equ	h'0e'
Status_temp	equ	h'0f'
Flag_register	equ	h'10'
#define shift	Flag_register,0
	 org	H'0000'
	 goto	start
	 org	H'0004'
	 goto	Int_Service
start	 bsf	STATUS,RP0
	 movlw	B'10010111'
	 movwf	OPTION_REG
	 bcf	STATUS,RP0
	 clrf	PORTB
	 bsf	STATUS,RP0
	 clrf	TRISB
	 bcf	STATUS,RP0
	 clrf	TMR0
	 movlw	B'10100000'
	 movwf	INTCON
	 clrf	Flag_register
	 movlw	Speed_value
	 movwf	Counter
	 goto 	main
Int_Service
      movwf	W_temp
      swapf	STATUS,w
      movwf	Status_temp
      btfss	INTCON,T0IF
      goto	end_int
TMR0_int
      decfsz	Counter,f
      goto	end_int
      bsf	shift
      movlw	Speed_value
      movwf	Counter
end_int	
      bcf	INTCON,T0IF
      swapf	Status_temp,w
      movwf	STATUS
      swapf	W_temp,f
      swapf	W_temp,w
      retfie
main  movlw	D'8'
      movwf	Shift_cunter
      movlw	B'00000001'
      movwf	PORTB
      bcf	STATUS,C
shift_again
      btfss	shift
      goto	shift_again
      rlf	PORTB,f
      bcf	shift
      decfsz	Shift_cunter,f
      goto	shift_again
      goto	main
      END